This invention relates generally to a venting system for vehicle airbags, and more particularly to the configuration of the vent of an airbag.
Inflatable airbags are inflated by gas directed into the airbag in response to a vehicle experiencing a sudden deceleration above a predetermined threshold. The inflated airbag absorbs energy resulting from the movement of an occupant within the vehicle compartment against the airbag. The energy absorbed by the airbag is dissipated to minimize rebounding the occupant from the airbag.
One way to dissipate the energy absorbed by the airbag is to vent the inflation fluid from the airbag. This venting occurs either through the porous bag material or through discrete vents or openings in the cushion. Typically, the vent opening has a circular shape. The vent opening is formed by cutting circular pieces of material from the airbag. Often, the discrete vent openings are reinforced with a panel sewn to the material of the airbag around the vent opening. It is thought that this reinforcement structure reduces stretching of the vent opening allowing for better control of the discharge of inflation fluids from the bag. Often, the edges of the material of the airbag surrounding a vent may fray. There is a concern in the industry that this frayed material may lead to a tear initiation site or may interact with the hot inflation gases to produce undesirable byproducts.
In accordance with one aspect of the present invention, an inflatable airbag is provided for, when inflated, restraining the vehicle occupant during a collision. The airbag includes a fabric material having an outer surface and an inner surface. The inner surface defines a chamber in which inflation fluid is directed to inflate the airbag. The fabric material includes at least one pair of generally perpendicular slots defining a vent therein. The generally perpendicular slots define four triangular flap portions which when opened define a square vent opening. When hot exhaust gases leave the cushion the generally triangular flap portions fold out of the way reducing the exposure of the thread ends to the discharged gases. It is particularly relevant to note that in contrast to known designs, these flap portions need not be sewed onto the cushion material but interact with the discharging gases upon deployment.
In accordance with another aspect of the present invention, a method of forming an airbag from airbag material comprising the steps of creating a pair of generally perpendicular cuts at a location in the airbag material, and sewing the airbag components together to define an inner chamber for accepting the inflation gases. Preferably, the pair of generally perpendicular cuts define at least four triangular flaps in the airbag material such that upon inflation of said airbag, said triangular flaps open up to define a square vent opening.